access to jest.fn()'s [enhancement]

It would be nice if the mocked jest.fn()'s were easily available so that toHaveBeenCalledWith() can used.

For example, when testing a getXXX function, I don’t really need to test that the value I just mocked is being returned as much as I need to make sure that the findOne function was actually called on the model with the proper parameters.

In a couple contrived jest tests, I’d see this working as such:

it('should call findOne with the _id', async () => {
  await getMyDocument('some_id');
  expect(mockingoose.MyDocument.findOne).toHaveBeenCalledWith({_id: 'some_id'});
});

it('should call findOne with the _id and isActive flag', async () => {
  await getMyDocument('some_id?isActive=true');
  expect(mockingoose.MyDocument.findOne).toHaveBeenCalledWith({_id: 'some_id', isActive: true});
});

[ironforward]

@alonronin oh cool, jest.clearAllMocks() definitely will help reduce mistakes.

I checked MyDocument.Query.prototype.exec.mock.calls and all I get is [ [] ]. So that’s useful for expect(MyDocument.Query.prototype.exec).toHaveBeenCalled(); but unless I’m doing something wrong I don’t think it’ll allow me to check the query being executed

[ironforward]

ah I see; I guess in case other people find their way here, this seems to be a valid way of doing it:

expect(MyDocument.Query.prototype.findOne).toHaveBeenCalledWith({ _id: 'some_id' }, undefined);

fyi, if you forget the second parameter then you’ll get a blank failure message, pays to remember that while the second parameter to findOne is optional, jest’s expect doesn’t care and expects you to declare that it will be undefined.

But the real gotcha in this is that the jest.fn never clears, so you must change your beforeEach to be as such:

beforeEach(() => {
  mockingoose.resetAll();
  MyDocument.Query.prototype.findOne.mockClear();
});

Otherwise one test’s calls will carry over into another test’s expectation and you will get false-positives.